No matter how carefully a meal is planned, sometimes there are leftovers. Although often the butt of food jokes, if prepared and reheated properly, leftovers are a blessing to busy cooks. In fact, many time-conscious cooks prepare special dishes, such as potatoes au gratin, with the intention of freezing and reheating them later. Potatoes au gratin, rich with cream and cheese, can turn a simple main dish into a special meal and aren't hard to reheat properly.
Remove the frozen potatoes au gratin from the freezer. Leave moisture-resistant paper or foil on the top of the pan. Place the container in the refrigerator to partially thaw.
Remove the moisture-resistant paper from the top of the pan. If the potatoes look dry, pour a small amount of milk on top; depending upon the amount of potatoes, this can range from 1/4 to 1/2 cup.
Sprinkle shredded cheese on top of the potatoes. You can use the same variety used in the original recipe or another variety to add a different taste.
Cover the pan with aluminium foil and place in a preheated 400-degree oven. Bake until the internal temperature of the potatoes au gratin reaches 73.9 degrees C.
Potatoes au gratin can be frozen for up to two weeks.
Do not refreeze potatoes au gratin after they have been frozen and reheated once.